Oil platforms may be used in offshore oil and gas production. In the operation of offshore oil platforms, electronics may be installed under water (e.g., for controlling functions of a subsea Christmas tree or a subsea blowout preventer). More recently, subsea processing facilities are being established in which processing equipment such as electrically driven pumps and gas compressors are relocated to the ocean floor. The subsea processing facility may require a power grid as well as control, monitoring and communication systems. It is to be provided that the installed equipment operates reliability even under the high pressures exerted by the sea water at great depths of water of, for example, more than 1000 or even 2000 meters.
To protect equipment from overcurrents or short-circuits, fuses that interrupt an electrical connection if the current through the fuse becomes too large may be installed. A conventional fuse includes a fuse body that may be made of ceramic, glass, plastic, fiberglass or the like, and a fuse element. The fuse element may be a metal strip or wire and is connected between two electrical terminals of the fuse. At currents above the rated current, the fuse element melts, thereby interrupting the electrical circuit. The faulty circuit may thus be isolated, whereby damage to other electric components of the system may be prevented.
For providing a fuse for subsea applications, a conventional fuse may be placed into a pressure resistant canister that is maintained at a pressure of about one atmosphere. The canister is to be thick walled in order to withstand the high pressures at water depths of more than 2000 m. Sophisticated penetrators capable of bridging such high pressure differences are further used to provide an electrical connection to the fuse through the walls of the canister. This solution of providing a fuse for a subsea application is very cost intensive due to the canister and the penetrators and further uses a considerable amount of space. The canister is also very heavy.
Solutions in which electric components are placed in pressure compensated canisters have also been provided. The canisters are filled with a dielectric liquid, and a pressure is maintained inside the canister that is almost equal to the surrounding water pressure. Standard fuses may be incompatible with such an environment. The dielectric liquid changes the properties of a conventional fuse dramatically. The fuse will still be capable of breaking a current when triggered, but this will cause an explosion inside the fuse, which may be detrimental to other electric components (e.g., due to a shockwave or shrapnel). The combustion products of the explosion may contaminate the surrounding dielectric liquid severely. This may cause failures in other components exposed to the dielectric liquid. Conventional fuses may thus not be used in a pressurized environment.